Claude Lorius, 70, is living proof that a career studded with brilliant scientific advances can begin almost by accident, by simply responding to an ad on a bulletin board, for example. Like the ad he read one day in 1955 on the walls of the University of Besançon (which would lead to a keen appreciation for the frozen southern pole) is now etched in his memory: “Needed: young researchers to join scientific excursions organized in conjunction with the International Geophysical Year.”

Two years later, Lorius, now a fresh initiate to the emerging science of glaciology after his stint in Greenland, was wintered down with two companions at Charcot Station, a small base camp perched 2,400 meters above Antarctica’s continental glacier. The purpose of the mission was three-fold: complete a radiative assessment of the surface, take samples of the summer and winter layers, and determine snow accumulation and temperatures in situ. The workload was heavy, but it was an ideal opportunity to witness, up close and for the first time, the indescribably cold and dense desert and to become completely enamored by this “mercilessly hostile” vastness, which he again visited in 1959 during a 1,400 km American-sponsored excursion.

Their objective was to measure the accumulation, temperature, altitude, and thickness of the ice, essential data for modeling the flow of the ice sheet. “The samples provided the basis for a relation that is still used today – one that allows us to obtain the temperature of the air from a measurement of the oxygen and hydrogen isotopes that make up ‘solid water’. This first point was the focus of a thesis I defended in 1963”, Lorius explained. “Most importantly, it provided us thereafter with a means of characterizing the successive seasonal layers and gave us a ice flow tracer and enabled us to reconstitute past temperatures.”

After several summer excursions, Claude Lorius led the 1965 winter campaign to the coastal base at Adélie Land, where core drilling was carried out on the ice that had traveled 1000 kilometers and marked by a moraine. A casual observation elicited a sudden interest in the bubbles of air often trapped inside ice: “It was when I saw them burst as ice cubes melt in a glass of whisky that it occurred to me they would hold vital information about the altitude the ice was formed at, and most importantly, the air bubbles were reliable and unique indicators of the composition of the air – something we would prove over the years,” Lorius recalled.

The team he organized would eventually join CNRS’s Laboratoire de Glaciologie at Grenoble, whose name was later amended to became the
“Laboratoire de Glaciologie et Géophysique de l’Environnement.” Once the techniques for dating and interpreting the ice sheet archives were finalized and the ice core drilling equipment – capable of drilling to a depth of 1,000 meters – was ready, one critical obstacle still remained: inadequate resources. How could a heavy drilling operation in the central regions of Antarctica be conducted when the funds provided by France’s polar expeditions were inadequate? Answer: cooperate with the researchers and logistics specialists from the U.S., Great Britain, Australia, France and the former U.S.S.R. in conjunction with the activities of the Programme international de glaciologie antarctique.

At the end of 1974, Claude Lorius left for the dry air of the Dome Concorde, a high plateau located in central Antarctica, where he would also return to in 1977. The ice he excavated at a depth of 900 meters was revealed to be about 35,000 years old. It allowed the scientific community to broaden its understanding of the end of the last ice age (about 20,000 years ago) – the subsequent thaw and warm period has now lasted for 10,000 years.

The conclusions reached by Swiss and French researchers were explosive: the levels of greenhouse gases (carbon dioxide and methane) 20,000 years ago were markedly lower that those recorded during the warm period! To support this finding, it was necessary to go further back in time, past the previous ice age, and get core samples from the last warm interglacial period that took place some 100,000 years ago. The deep drilling conducted at Camp Century, Greenland, and at Byrd, in Antarctica, by the Americans, the Danes, and the Swiss, “provided promising results over a period extending over several thousands of years,” but these results nevertheless pose certain problems of interpretation. Fortunately, another series of samples exists at Vostok, the most remote (1,400 km from the nearest coast) and coldest station on Earth (with mean temperatures of -70° and lows reaching -89° in the winter, and -40° in the summer). In short, this outpost, where a handful of soviet technicians involved in the Antarctic Expeditions have been drilling up to a depth of 2,200 meters deep into the polar ice sheet since the 1950s, has acquired mythical status among polar specialists. Thanks to the support of the Arctic and Antarctic Institute of Leningrad, the Geographic Institute of Moscow, and the National Science Foundation (U.S.), Claude Lorius and his two companions were able to set foot on this nook of frozen planet at the end of 1984, in the midst of the cold war. “The conditions were rustic and it took a strong heart,” he recalled. But the harvest reaped by the ice core drill met all his expectations. “For the first time, we had a series of results undisturbed by any ice flow for over 150,000 years, which comprises all the latter climatic cycles in the quaternary era.”

Once back in France, his treasure-trove (2,000 samples taken from 3 tonnes of ice cores), pored over by a squad of experts, began to reveal its secrets. The results would hit the headlines of the journal Nature in 1987 and confirm the multi-millennial versatility of the Earth’s climate. “A long ice age occurred between the current interglacial period and the interglacial period that existed about 120,000 years ago. The measurement of a new parameter (oxygen 18 in the bubbles) also enabled us to correlate the variations in temperature with those obtained from marine sediments: glacial and interglacial periods caused periodic variations of up to 120 meters in the level of the sea.”

Another major scoop: the alternating periods of global warming and cooling, attributed to (weak) variations in the energy emitted by the sun resulting from the Earth’s position, correspond to significant fluctuations in the composition of greenhouse gases in the atmosphere. “Carbon dioxide (CO2) concentrations, for example,” explained Claude Lorius, “increased by 40 % during the last deglaciation, while methane gas (CH4) levels doubled.” Naturally, it would be impossible to attribute this yo-yo effect to human activity: "Fluctuations in CO2 levels are regulated by the oceans through a variety of physical, chemical and biological processes. Living organisms do play a role in climatic changes. For hundreds of thousands of years, the temperatures and the concentrations of aerosols and greenhouse gases have varied between relatively constant minimum and maximum levels. The Earth’s climate is naturally self-regulating, varying between these two well-defined stable states.” But we must admit that “current greenhouse gas levels are unprecedented, higher than anything measured for hundreds of thousands of years, and directly linked to man’s impact on the atmosphere. The conclusions reached from a study of glacial archives lend credence to the assertion that the planet has warmed considerably throughout the 21st century, with potentially dire consequences on water supplies, agriculture, health, biodiversity, and in a broader sense, the man’s living conditions.” Greater awareness of this risk acquired “through his study of ice cores”, which bear further imprints of man’s activities, prompted Claude Lorius to respond to media requests (i.e. books, conferences, radio and television programs) over the years – while maintaining involvement “in a university think tank devoted to climate, energy, and society.” It is a “vast subject,” he insisted, “in which learning will be called on to serve as an arbiter between divergent ecological, economic, social, and international approaches. The alarm we raised was heard, for certain problems including for example ozone levels and lead in gasoline, and some improvement has been noted. But in many other cases, like the climate for example, we have only heard statements of intention. We have to maintain the pressure to ensure new technologies are developed and attitudes continue to evolve (perhaps via the media?) – Of course, that’s easier said than done!”

With an undying longing for the upper latitudes, Lorius says his fondness for that icy realm, home to the snowy petrel and the emperor penguin, has found an enduring place in his heart. Throughout his entire career, Claude Lorius confessed he has been motivated by the appeal of diverse polar excursions. “I have spent winters, participated in long-distance treks, been in charge of a base camp, and taken part in many ice-core drilling operations.”

“Now, all these experiences seem scientifically coherent – although I can’t really understand why!”
Others will have little difficulty doing that. A nomad at heart, Lorius nevertheless confessed: “My last trip to Antarctica, in 1998, was my last. I won’t be going back. I did so many things there that I don’t want to have any regrets. I am sure that the glacial archives have not yet revealed all their secrets and that technological advances and the creativity of the researchers will yield many more avenues of research…”

Born February 27, 1932 in Besançon, Claude Lorius has a licence ès-sciences in physics (awarded in 1953), a diplôme d’études supérieures in physics (1954) and a doctorat ès-sciences in physics (1963). After participating in the excursions organized in conjunction with the International Geophysical Year (1957), Lorius defended his dissertation in 1963 before joining the CNRS, where he is now director emeritus of research. He was the assistant director of the Laboratoire de glaciologie et géophysique de l’environnement from 1979 to 1983, a laboratory located in Grenoble that he would head up from 1983 to 1988. Claude Lorius also held a number of responsibilities at the national level: within the CNRS; the Ministries of Research and the Environment; the French National Committee on Antarctic Research, from 1987 to 1994; and the French Institute for Polar Research and Technology, which he founded in 1992. He also led a number of French Polar Expeditions from 1984 to 1987.

At the international level, Lorius was a member of the World Climate Research Programme (OMM-ICSU) from 1980 to 1984, and the executive committee of " Past Global Changes " (IGBP) from 1989 to 1998. He contributed to the work of the Scientific Committee on Antarctic Research (ICSU), for which he assumed the duties of president from 1986 to 1990, and the International Arctic Science Committee, between 1991 and 1998. Within the ESF, he led a working group on glaciology from 1985 to 1993, and was a member of the European Committee on Oceanography and Polar Sciences (European Science Foundation and Commission of the European Community) from 1989 to 1997. Lorius was also a member of the executive committee of the Greenland Ice Core Project from 1989 to 1993, and he presided over the EPICA project (European Program for Ice Coring in Antarctica) from 1993 to 1995.

Awarded the Humbold Prize (1989), the Belgica Medal (1989), the Italgas Prize (1994), the Tyler Prize for Environmental Achievement (1996), and the Balzan Prize for climatology (2001), Claude Lorius is an officer of the Legion of Honor (1998), and a corresponding member, then member (since 1994) of the Académie des Sciences and the Académie des Technologies, created in 2000. He is also a foreign member of the Russian Academy of Science (1994), a member of the Academia Europaea (1989), and a European Geophysical Society Fellow (1999).

Claude Lorius has participated in a total of 22 summer and winter excursions to the polar ice sheets in Greenland and particularly in Antarctica (at Charcot in 1957, Dumont d’Urville in 1965, and Vostok in 1984). In all, this represents more than six years spent in the North and South Polar Regions. He also published over 100 articles in professional journals, among which Nature (which put his research on the Vostok ice sheet on its front cover in 1987 and 1993), and Science (1993). Claude Lorius also participated in a number of television programs and authored two books: Glaces de l’Antarctique : une mémoire, des passions, published by Odile Jacob (1991), and L’Antarctique (written with R. Gendrin, published by Flammarion (Collection Dominos, 1997).